Privacy advocates got access to Locate X, a phone tracking tool which multiple U.S. agencies have bought access to, and showed me and other journalists exactly what it was capable of. Tracking a phone from one state to another to an abortion clinic. Multiple places of worship. A school. Following a likely juror to a residence. And all of this tracking is possible without a warrant, and instead just a few clicks of a mouse.
You sure it’s still not phoning home? How do you know “off” is really “off” anymore with a modern phone? It’s not like an old flip phone that you can just pop the battery out. Sure it sounds paranoid, but we’re literally talking about something that used to be the realm of crackpots and cranks - “the government is tracking all of us 24/7!” Well, it seems that’s actually literally the case now.
Yes. When your phone is off, it is off.
If you’re paranoid you can buy a faraday bag.
The iPhone remote locator function still works when the phone is powered off. It doesn’t work when the battery is completely dead, but it does work when the phone is supposedly “powered off.” This is irrefutable proof that iPhones at least retain some of their functions even when you’ve “turned them off.”
I don’t want to encourage paranoia here but “off” does not mean “off”. Modern phones are almost never actually “powered down”. If you’re paranoid, turning your phone off is not enough. Leave it behind.
(Also a gap in your phone’s location history can also be used against you, fwiw.)